Microphysiology of synaptic transmision (S.W. Kuffler et al.). Much of the current work revolves around a study of the activation of the subsynaptic membrane by the action of chemoreceptors. Tests are made through the release of transmitter from nerve terminals and from micropipettes. Development of Sympathetic Junctions in Culture. D.D. Potter, E.J. Furshpan, et al. Neurons from the superior cervical ganglia of newborn rats will be isolated and grown in culture by methods previously described by this laboratory. The major points of interest will be: 1) to study further the cholinergic synapses formed by these neurons on each other; physiological, histochemical and electron microscopical methods will be used. 2) The influence of non-neural cells, especially cells from the heart, on the time course and extent of formation of the cholinergic synapses. Regenerating axon terminals are being examined in muscles and autonomic ganglia. The aim is to determine the successive steps in the terminals reformation and the role played by the axon, the postsynaptic cell and the Schwann cell in this process. The techniques will involve electrophysiology, histochemistry and morphology, including electron microscopy. Studies of Synaptic Chemistry in the Nervous System. E.A. Kravitz et al. The overall aim of this project is to determine the chemical differences between identified neurons that contribute to their functional differences. We shall combine physiological and anatomical techniques with microbiochemical studies in the nervous system of the lobster, where neurons are large and relatively few in number. BIBLIOGRAPHIC REFERENCES: Hartzell, H.C., Kuffler, S.W. and Yodhikami, D. Postsynaptic potentiation: Interaction between quanta of acetylocholine at the skeletal neuromuscular synapse. J. Physiol. (Lond.) In Press. Hartzell, H.C., Kuffler, S.W. and Yoshikami, D. The number of acetylcholine molecules in a quantum and the interaction between quanta at the sybsynaptic membrane of the skeletal neuromuscular synapse. Cold Spring Harbor Symp. Quant. Biol. 40. In Press.